SYSTEM AND METHOD TO STABILIZE RADIOACTIVE ISOTOPES

Abstract

A method for stabilizing radioactive isotopes includes preparing a liquid solution and mixing the liquid solution with Cement Kiln Dust (CKD) powder to form a solid material. The method may further include crushing the solid material into particles and passing radioactive water through the solid material to remove radioactive isotopes from the radioactive water and stabilize the radioactive isotopes.

Claims

1. A method for stabilizing radioactive isotopes, the method comprising: preparing a liquid solution; mixing the liquid solution with Cement Kiln Dust (CKD) powder to form a solid material; crushing the solid material into particles; and passing radioactive water through the solid material to remove radioactive isotopes from the radioactive water and stabilize the radioactive isotopes.

2. The method of claim 1, wherein preparing the liquid solution comprises adding iron, sulfur, copper, calcium, and magnesium into hot water to form a first mixture.

3. The method of claim 2, wherein mixing the liquid solution with the CKD powder to form the solid material comprises mixing and combining about 5 weight % of the first mixture with about 20-40 weight % of the CKD powder to produce a second mixture.

4. The method of claim 3, further comprising adding about 10-40 weight % liquid sulfur and xanthan gum glyoxal to the second mixture to produce a third mixture.

5. The method of claim 4, further comprising adding and mixing about 10-30 weight % sodium hydroxide with the third mixture to produce a fourth mixture.

6. The method of claim 5, further comprising adding about 20-100 weight % hot water with the fourth mixture to produce a fifth mixture.

7. The method of claim 6, further comprising separating a first cut solid and a second cut aqueous extract from the fifth mixture.

8. The method of claim 7, further comprising preparing a second cut solid and a second cut aqueous extract from the first cut solid and the second cut aqueous extract.

9. The method of claim 8, further comprising preparing a third cut solid and a third cut aqueous extract from the second cut solid and a second cut aqueous extract.

10. The method of claim 9, further comprising combining the third cut aqueous extract with about 25 weight % cement to produce the solid material.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Illustrative embodiments of the present invention are described herein with reference to the accompanying drawings, in which:

[0022] FIG. 1 is a first flow chart of a procedure for preparing a first-cut aqueous extract in accordance with the present disclosure.

[0023] FIG. 2 is a second flow chart of a procedure for preparing a second-cut aqueous extract in accordance with the present disclosure.

[0024] FIG. 3 is a third flow chart of a procedure for preparing a third-cut aqueous extract in accordance with the present disclosure.

[0025] FIG. 4 is a fourth flow chart of a process for making solids in accordance with the present disclosure.

[0026] FIG. 5 is a schematic diagram of a treatment system in accordance with the present disclosure.

DETAILED DESCRIPTION OF INVENTION

[0027] For a further understanding of the nature and function of the embodiments, reference should be made to the following detailed description. Detailed descriptions of the embodiments are provided herein, as well as, the best mode of carrying out and employing the present invention. It will be readily appreciated that the embodiments are well adapted to carry out and obtain the ends and features mentioned as well as those inherent herein. It is to be understood, however, that the present invention may be embodied in various forms. Therefore, persons of ordinary skill in the art will realize that the following disclosure is illustrative only and not in any way limiting, as the specific details disclosed herein provide a basis for the claims and a representative basis for teaching to employ the present invention in virtually any appropriately detailed system, structure or manner. It should be understood that the devices, materials, methods, procedures, and techniques described herein are presently representative of various embodiments. Other embodiments of the disclosure will readily suggest themselves to such skilled persons having the benefit of this disclosure.

[0028] Reference will now be made in detail to the present preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numerals are used in the drawings and the description to refer to the same or like parts.

[0029] FIG. 1 is a first flow chart depicting a procedure/method for preparing a first-cut aqueous extract in accordance with the present disclosure. At step 100, the method may include adding and mixing trace amounts (i.e., parts per million as measured in ground water) of iron, sulfur, copper, calcium, and magnesium into hot water, which may form a first mixture. At step 102, the method may include combining about 5 weight % hot water (e.g., the first mixture), with about 20-40 weight % Cement Kiln Dust (CKD) powder for producing a second mixture.

[0030] Cement is a chemical substance that sets, hardens, and adheres to other materials for binding them together. Cement, seldom used on its own, is typically used to bind sand and gravel (aggregate) together. Cement, when mixed with fine particles, produces mortar for masonry, or when mixed with sand and/or gravel, produces concrete, the most widely used material in existence, which is behind only water as our most-consumed resource. Cements, usually inorganic and often lime or calcium silicate based, are characterized as either hydraulic or the less common non-hydraulic, depending upon the ability of the cement chosen to set in the presence of water. Hydraulic cements (e.g., Portland cement) set and become adhesive through a chemical reaction between the dry ingredients and water. The chemical reaction results in mineral hydrates that are not very water-soluble and thus quite durable in water and safe from chemical attack. This allows setting in wet conditions or under water, further protecting the hardened material from chemical attack. CKD is a residue produced during the manufacture of cement.

[0031] At step 104, the method may include adding about 10-40 weight % liquid sulfur and xanthan gum glyoxal, to the hot water mixture of CKD powder (or the second mixture) for producing a third mixture. At step 106, the method may include adding and mixing about 10-30 weight % sodium hydroxide to produce a fourth mixture. At step 108, the method may include adding about 20-100 weight % hot water, as desired, with the fourth mixture to produce a fifth mixture. At step 110, the method may include separating the solid and aqueous phases from the fifth mixture. At step 112, the method may include transferring a first cut aqueous extract to further processing (as described below in conjunction with FIG. 4). At step 114, the method may include transferring first cut solids that result to a second cut procedure. Stated another way, the method may include transferring the first cut solids to another procedure described in FIG. 2 for producing a second cut aqueous extract.

[0032] FIG. 2 depicts a second flow chart of a procedure for preparing a second-cut aqueous extract in accordance with the present disclosure. At step 116, the method may include adding, to the first cut procedure solids, about 5 weight % hot water into which iron, sulfur, copper, calcium, and magnesium are combined to produce a sixth mixture.

[0033] At step 118, the method may include adding and mixing, into the hot water (e.g., the sixth mixture), about 30-50 weight % sulfur, xanthan gum, glyoxal (about 10-45 weight % purity), calcium hydroxide, and about 10-30 weight % glucose to produce a seventh mixture. At step 120, the method may include adding and mixing about 10-30 weight % sodium hydroxide to the seventh mixture to produce an eighth mixture. At step 122, the method may include adding about 20-100 weight % hot water, as desired, to the eighth mixture to produce a ninth mixture. At step 124, the method may include separating the solids and aqueous phase from the ninth mixture. At step 126, the method may include transferring a second cut aqueous extract to further processing (as described below in conjunction with FIG. 4). At step 128, the method may include transferring second cut solids that result to a third cut procedure. Stated another way, the method may include transferring the second cut solids to another procedure described in FIG. 3 for producing a third cut aqueous extract.

[0034] FIG. 3 depicts a third flow chart of a procedure for preparing a third-cut aqueous extract in accordance with the present disclosure. At step 130, the method may include adding, to the second cut procedure solids (from the procedure described above in conjunction with FIG. 2), about 5 weight % hot water into which iron, sulfur, copper, calcium, and magnesium are combined to produce a tenth mixture.

[0035] At step 132, the method may include adding and mixing, into the hot water (e.g., the tenth mixture), about 30-50 weight % sulfur, xanthan gum, glyoxal (about 10-45 weight % purity), calcium hydroxide, and about 10-30 weight % glucose to produce an eleventh mixture. At step 134, the method may include adding and mixing about 10-30 weight % sodium hydroxide to the eleventh mixture to produce a twelfth mixture. At step 136, the method may include adding about 20-100 weight % hot water, as desired, to the twelfth mixture for producing a thirteenth mixture. At step 138, the method may include separating the solids and aqueous phase from the thirteenth mixture. At step 140, the method may include transferring a third cut aqueous extract to process (as described below in conjunction with FIG. 4). At step 142, the method may include transferring third cut solids to treatment system (as described below in conjunction with FIG. 5).

[0036] FIG. 4 depicts a fourth flow chart of a process for making solids in accordance with the present disclosure. In this process, the first-cut, the second-cut, and the third-cut aqueous extracts may be used at predetermined amounts to remove/stabilize radioactive atoms from water, materials, and surfaces. Each of the first-cut, the second-cut, and the third-cut aqueous extracts may be contaminated with predetermined radioactive materials. The contaminated aqueous extracts are combined with cement, as illustrated in FIG. 4, for stabilizing radioactive isotopes and attenuating radioactivity, to reduce the cost of their transportation and disposal.

[0037] At step 144, the method may include combining the third cut aqueous extract with about 25 weight % cement and mixing to produce solids. At step 146, the method may include crushing the solids to 2 inches (minus) particle size (meaning that the particles thus produced can pass through known commercial screens having 2-inch diameter openings) for liquid filtration for water/liquid contamination. At step 148, the method may include adding the crushed material to the system shown in FIG. 5.

[0038] At step 150, the method may include mixing, to the first cut and the second cut extract, about 25 weight % cement and about 20 weight % vermiculite to produce solids. At step 152, the method may include forming and drying solids, making a lightweight radioactivity attenuating/shielding product. As used herein, lightweight refers to a density less than the density of lead (708 lb/ft.sup.3), steel (489 lb/ft.sup.3), and concrete (150 lb/ft.sup.3). For example, the radioactivity attenuating/shielding product disclosed herein may have a density of about 60 lb/ft.sup.3.

[0039] FIG. 5 depicts a block diagram of a treatment system 200 in accordance with the present disclosure. The treatment system 200 may be configured to stabilize water and/or other liquids contaminated with radioactive material by removing radioactive material and/or reducing radioactivity levels from water and/or other liquids, in accordance with the present disclosure. The system 200 includes a holding tank 210 from which the contaminated water and/or other contaminated liquids or fluids are conveyed via a conduit 220 into a treatment zone 230 (or a treatment box). The treatment zone 230, which includes an outlet conduit 240, may be divided into a plurality of compartments 232, 234, 236, and 238 that are interconnected for permitting fluid flow from the conduit 220, though the plurality of compartments 232, 234, 236, and 238, seriatim, and then to the outlet conduit 240. The outlet conduit 240 may transfer the water and/or the other liquids or fluids treated by the treatment zone 230 (to remove radioactive material and/or reduce their radioactivity levels) to an outlet discharge tank 250, used as a holding tank until water and/or other liquids treated by the treatment zone 230 are desired for use. Radioactive liquid, e.g., water, is passed through the treatment zone 230 at a predetermined rate with the crushed solid product. The radioactive contaminants are attracted to the solid crushed material where they are bound. Liquid passing out of the treatment zone 230 may be free from contaminant or have a greatly reduced level of contamination.

[0040] The solid material may be used by pumping radioactive water through the treatment system 200 containing the solid product/material that causes the radioactive isotope to bind onto the solid product removing the radioactivity from the water and stabilizing the isotope on the solid product where it stays permanently bound to the solid product. Although the product is designed for radioactive isotopes, the method of present disclosure may be used to stabilize heavy metals as well. Details of a few example tests are provided below.

Example 1: Procedure for Testing 99Tc Removal by PROTECTORATE (Rad Products Family Name) and Results

[0041] Procedure. 99TC (Technetium) was added to (oxic) aqueous solutions of BX (2.sup.nd-cut aqueous extract, step 126, FIG. 2) and BC (1.sup.st-cut aqueous extract, step 112, FIG. 1) or to suspensions of ROC (rocks, i.e., crushed solids, without PROTECTORATE) and ROC-P (with PROTECTORATE). 99Tc was added as pertechnetate species (TcO.sub.4-) at 1200 dpm/mL (approximately 3?10.sup.?10 mol/L). Concentrations of BX and BC were each 1% by volume. The suspension concentration of ROC and ROC-P was 40 g/L.

[0042] First sampling after 15 minutes of reaction: Samples were mixed end over end then centrifuged five minutes at 4,500 rpm. 0.50 mL of each sample was removed and mixed with 5 mL HiSafe3 LSC cocktail (Liquid Scintillation counting cocktail) and measured for 15 minutes per sample on a Hidex 300SL (Scintillation counter).

[0043] Results of first sampling, after 15 minutes of reaction, are summarized in Table 1 below.

TABLE-US-00001 TABLE 1 Signal Measured conc. Error measured % Error % Sample ID counts/min. Error (dpm/mL) conc. (dpm/mL) removal removal Background 43.26 error signal Control-I-1 678 6.723095 1269.5 26.9 0.0% 0.0% ROC-I-1 660 6.63325 1233.5 26.5 2.8% 0.1% ROC-P-I-1 685 6.757712 1283.5 27.0 ?1.1% 0.0% BX-I-1 653 6.597979 1219.5 26.4 3.9% 0.1% BC-I-1 658 6.623192 1229.5 26.5 3.2% 0.1%

[0044] At second sampling, after three days of reaction, BX and BC each included a visible precipitate, yellow/brown in color, initially, which dissipated. Precipitates appeared white/grey, with the precipitate in BX being present more as a film on walls of the sample vial, presenting a precipitate which had not been removed from solution by centrifugation.

[0045] Results of second sampling, after 3 days of reaction, are summarized in Table 2 below.

TABLE-US-00002 TABLE 2 Signal Measured conc. Error measured % Error % Sample ID counts/min. Error (dpm/mL) conc. (dpm/mL) removal removal Background 40 error signal Control-I-2 678 6.723095 1269.5 26.9 0.0% 0.0% ROC-I-2 675 6.708204 1263.5 26.8 0.5% 0.0% ROC-P-I-2 661 6.638273 1235.5 26.6 2.7% 0.1% BX-I-2 548 6.044281 1009.5 24.2 20.5% 0.7% BC-I-2 649 6.57774 1211.5 26.3 4.6% 0.1%

[0046] Summary and analysis of 1.sup.st and 2.sup.nd sampling data presented in Tables 1 and 2 is provided below.

[0047] The 2.sup.nd-cut aqueous extract stream (step 126 in FIG. 2) noticeably removed Tc, which appears to have been facilitated by the formation of the white/grey precipitate in the sample, which likely either incorporated the TC or generated a surface for the TC to sorb onto. In either case, it is most likely that the TC is being removed by reduction of TC(VII) to TC(IV), which is quite a difficult challenge, given the relatively high pH of these solutions (pH values ranging from 10 to about 11) and the fact they occur under toxic conditions.

[0048] Table 3 provides comparative analyses of radioactive activity levels before and after treatment.

TABLE-US-00003 TABLE 3 Sample Methods Results DL RL Units PF DF Water, Before See note 1 197000 33.5 100 ?g/L 1.00 500 Water, After See note 1 68.1 0.0670 0.200 ?g/L 1.00 1 Misc. Solids See note 2 0.165 0.000670 0.00200 mg/L 10.0 1

[0049] Comments: Note 1. Prep method performed was EPA 200.2; and the description is ICP-MS 200.2 PREP; also, the analytical method performed was method 1; and the description is EPA 200.8. Note 2. Prep methods performed were SW846 1331, a description of which is SW846 1311 TCLP Leaching; and SW846 3010A, a description of which is TCLP SW 846 3010 Acid Digestion. Also, DL is a Detection Limit. RL is a Reporting Limit. PF is a Prep Factor. DF is a Dilution Factor.

[0050] Additional illustrative examples of the present subject matter are made as follows:

Example 2: Removal/Stabilization of Heavy Metals and Radioactive Metals from Water

[0051] A liquid product, to stabilize heavy metals, including radioactive metals, is prepared as follows: (Item 1) First, water which includes iron, sulfur, copper, calcium, and magnesium ions is heated to a predetermined temperature. (Item 2) Next, a powderwhich includes the following ingredients in measured amounts: crystalline silica, tricalcium silicate, dicalcium silicate, tricalcium aluminate, tetra-calcium aluminoferrite, calcium sulfate dihydrate, calcium oxide, carbon, cadmium, chromium, magnesium, nickel, lead, and chlorideis prepared as a feedstock. (Item 3) Thereafter, the feed stock ingredients (item 2) are added and mixed into the hot water (item 1), to produce an aqueous mixture. Then, the following ingredients, in measured amounts, are added and mixed into the aqueous mixture: sulfur, glyoxal, calcium hydroxide, coal, glucose, and sodium hydroxide.

Example 3: Solids Stabilization of Heavy, Radioactive Metals, Removing them from Water

[0052] Combine the hot water (Item 1) described in Example 2 with measured amounts of the following ingredients: tricalcium silicate (3CaOSiO.sub.2), dicalcium silicate (2CaOSiO.sub.2), tetra-calcium aluminoferrite (4CaO.Math.Al.sub.2O.sub.3.Math.Fe.sub.2O.sub.3), calcium sulfate (CaSO.sub.4), tricalcium aluminate (3CaOAl.sub.2O.sub.3), calcium sulfate dihydrate (gypsum) (CaSO.sub.4-2H.sub.2O), calcium carbonate (CaCO.sub.3), and crystalline silica quartz (SiO.sub.2), to produce a stabilized solid containing radioactive metals of Example 3.

Example 4: Manufacture of a Light-Weight Solid Material Used for Attenuating Radioactivity

[0053] Add/Mix vermiculite (Mg, Fe.sup.2+, Fe.sup.3+).sub.3[(Al, Si).sub.4O.sub.10](OH).sub.2.Math.4H.sub.2O into Example 3.

Example 5: Foam, Plastic, Chemical Product Radiation Attenuation

[0054] In another example, various thickness of a product disclosed herein (BC and/or C) were tested to determine the ability of the product to attenuate radioactivity as compared to lead (Pb), using a Ludlum 9DP-1 ion chamber. BC refers to a product with a 1.sup.st cut aqueous extract and C refers to chemical. Using Cesium 137 as a radioactive source having a calculated radioactivity of 50 mR/hr., radioactivity was measured at 0.99 meters from the source. The results are presented in Table 4.

TABLE-US-00004 TABLE 4 Measured Radiation, Material Component mR/hr. % reduction ? Pb 4.0 92.0 ? Pb 16.3 67.4 4 BC 21.0 58.0 6 BC 14.2 71.6 8 BC 9.0 82.1 4 C 27.0 46.0 6 C 29.7 40.6 8 C 24.9 50.2 4 BC + 4 C 13.6 72.8 12 BC + steel frame 3.2 93.6

[0055] Except as may be expressly otherwise indicated, the article a or an if and as used herein is not intended to limit, and should not be construed as limiting, the description or a claim to a single element to which the article refers. Rather, the article a or an if and as used herein is intended to cover one or more such elements, unless the text expressly indicates otherwise.